This invention relates generally to the field of orthopedic medicine, and more particularly, to a medical bandaging product and material that includes a warp knitted, double-layered fabric substrate. The substrate material disclosed herein achieves enhanced strength as a result of novel structural characteristics not found in the prior art.
Medical bandages for use in the treatment of injuries, such as broken bones requiring immobilization of a body member, are generally formed from a strip of fabric or scrim material impregnated with a substance that hardens into a rigid structure after the strip has been wrapped around the body member. The hardening substance traditionally used in carrying out this procedure is plaster-of-paris.
Conventional practice has been to fabricate a cast or splint upon an injured limb by initially applying to the limb a protective covering of a cotton fabric or the like, and then overwrapping the covering and limb with a woven cloth impregnated with plaster-of-paris that has been wetted by dipping in water immediately prior to application. This practice is still in widespread use, but possesses several significant disadvantages. For example, the above-described application procedure is messy, time consuming, requires several components, and requires considerable skill.
In order to alleviate the above-recited disadvantages of the conventional application procedure for plaster-of-paris casts and splints, unitary splinting materials have been devised and are disclosed in, for example, U.S. Pat. No. 3,900,024, U.S. Pat. No. 3,923,049, and U.S. Pat. No. 4,235,228. All of these patents describe a padding material with a plurality of layers of plaster-of-paris impregnated cloth.
A significant advance in the art of casting and splinting is disclosed in U.S. Pat. No. 4,411,262 and U.S. Pat. No. 4,502,479. The casting materials disclosed in these patents include bandaging materials that incorporate a substrate formed from a plurality of flexible fabric layers, such as fiberglass, impregnated with a moisture-curing resin. These bandaging materials are enclosed in a moisture-free, moisture-impervious package until use. Compared to plaster-of-paris, these products are extremely lightweight, have a very high strength-to-weight ratio and can be made relatively porous, permitting a flow of air through the casting material. However, no provision has been made for moisture-curing systems that incorporate a substrate that is formed from a single layer of fabric, yet is strong and absorbent enough to be impregnated with amounts of moisture-curing resin comparable to those amounts absorbed by conventional multi-layered substrates.
U.S. Pat. No. 4,770,299 and U.S. Pat. No. 5,003,970, among others owned by the present applicant, each disclose roll-form synthetic bandaging products that include the ability to dispense desired lengths of bandaging material when needed, while sealing the remaining length of material for later use. Similar products are also sold in precut lengths sealed in a single use, moisture-impervious envelope.
Both the conventional plaster-of-paris cast and splint products, and the more recent moisture-curable resin cast and splint products possess certain disadvantages. Plaster-of-paris casts are bulky, heavy and difficult to apply. Even though moisture-curable resin bandage products are lightweight, durable and relatively easy to apply, such products remain relatively expensive to produce due to the need to carefully assemble multiple layers of fabric into a long stack of precisely-aligned layers.
This invention combines the advantages of both plaster-of-paris and moisture-curable resin systems while avoiding their respective disadvantages. Unlike prior art resin systems that employ multiple layers of resin-impregnated substrate layers, the resin system of the present invention takes advantage of a single layer of warp-knitted fabric. Substrates of the general type described in this application are known, and are disclosed in, for example, applicant's own issued U.S. Pat. No. 7,972,288, U.S. Pat. No. 7,960,603 and U.S. Pat. No. 7,854,712. This unique substrate fabric employs a continuous inlaid stitch. This results in a double-knitted fabric that has a lighter weight, yet retains the absorption capabilities of multi-layered substrates. Using a single layer of double-knitted fabric in the substrate further results in reduced production and labor costs in comparison with other synthetic cast products. For example, assembly of prior art, multi-layered substrates requires placement of the overlying fabric layers of the substrate by hand, which is a time consuming process. To ensure that the fabric layers do not separate, the layers must then be stitched together by running one or more seams along the entire length of the substrate. Use of a substrate having only one layer eliminates these labor-intensive layering and stitching steps, and results in a bandaging product that is more cost effective to produce.
Eliminating the multi-layered substrate structure also eliminates the rough, uneven edges present on prior art cured substrates. Such frayed edges are commonplace in prior art bandaging products having multi-layered substrates, and materialize after the resin in such substrates undergoes final curing. These rough edges cause irritation and damage to the skin of the patient upon whom the bandage is ultimately applied. In contrast, the substrate of the present invention has uniform side edges that result from using the single-layer of double-knitted fabric, rather than multiple, uneven fabric layers. This novel structure results in a medical bandage product having a moisture-curable substrate that is lighter in weight than conventional products, yet is stronger and more cost-effective to produce. Careful construction and a unique and counterintuitive relationship between the technical inner and outer surfaces and the space between the technical surfaces provide further enhancement in the quality of the substrate, both in comfort, ease of application and ultimate rigidity. More rapid hardening of the substrate provides a more realistic subjective impression of rigidity more in keeping with hardening rated in prior art fiberglass splinting and casting products.